Reset thermal switch



Dec. 12, 1939. 5, RIVERS I 2,183,518

RESET THERMAL SWITCH Filed May 18, 1938 1H /0 4 l3 AD 31 I}, a 2 r P- I A; u

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[771/677 for Durward J Bil/c714 B m m,

442 Zornega Patented Dec. 12, 1939 UNITED STATES PATENT OFFICE Rivers administratrix Rivers, deceased of said Durward 8.

Application May 18, 1938, Serial No. 208,520

2Claims.

This invention relates to means for interrupting an electrical circuit upon predetermined overloads or short circuits and has for a primary object the provision of a very compact and port- 5 able unit that may be interconnected into a circuit and disconnected therefrom simply by plugging it into or removing it from the customary plug connecting receptacle.

A further important object of the invention 10 is to provide a structure of the above indicated type which will require its removal from the circuit before it may be reset. A still further important object of the invention is to provide a circuit interrupter of the type indicated which 15 by reason of its peculiar structure cannot be varied in its rated current carrying load through a series of normal operations thereof or by any resetting operation.

These and further objects and advantages of so the invention will become apparent to those versed in the art in the following description of one particular form of the invention as illustrated in the accompanying drawing, in which Fig. 1 is a side elevation of a device embodying 25 the invention as applied to a motor;

Fig. 2, a side elevation of the structure in partial section;

Fig. 3, an opposite side elevation in like partial section;

30 Fig. 4, a transverse section on the line H in Fig. 3,

Fig. 5, a vertical section on the line 55 in Ma 4;

Fig. 8, a transverse section on the line 6-6 in 35 Fig. 5, and

Fig. 7, a wiring diagram.

Like characters of reference indicate like parts throughout the several views in the drawing.

'Reference is made to my U. S. Letters Patent 40 No. 2,125,126, issued July 26, 1938.

A body It is formed of any suitable insulating material to be generally rectangular in transverse cross-section. This body l has a longitudinal groove on each of its four side faces. A

45 thermostatic responsive element ll, preferably made out o! a suitable bi-metal, is formed to have a general L-shape with one arm extending along the length of the side slot i2, Fig. 3, and a shorter arm or foot turned around over the end 50 of the body ill where a foot l3 of a terminal prong I4 is carried thereagainst by any suitable means such as the screw I! which passes through the foot II, the end of the element II, and screwthreadedly engages in the body It, Fig. 5. I'his 5 terminal prong l4 bends around and downwardly sharply irom the foot l3 to follow in the groove on the left hand side of the body III, Fig. 3, and is carried downwardly beyond the lower end of the body It.

On the rear side of the body ID in the groove I I6 is mounted a bar or plate ll, Fig. 2, and a short length of a flexible ribbon-like conductor I8 has one end inserted under the lower end of this bar I1 and there compressively engaged by means of the securing screw l9 which screw- 10 threadedly engages in the side of the body Ill.

The body 10 is preferably provided, although not necessarily so, with an enlarged lower end or head 20 and the longitudinal slots of the body ID are carried on across this head. The head is slotted transversely across this lower end to inter-connect the side slots l2 and I6 to form the slot generally designated by the numeral 2|.

A switch arm 22, here shown as a flat plate or bar, is rockably carried in this slot 2! by any 20 suitable means to be pivoted at its end removed from the lower end of the element H.

In the form herein shown, the plate or arm 22 is secured to a U-shaped bracket 23, Fig. 2, the legs of which receive a pin 24 therethrough 25 and on which the bracket may rock freely. This pin 24 is passed through the head 20 to be irictionally retained thereby. The switch arm 22 is inter-connected with this bracket 23 as is also the conductor l8 so that electrical circuit may be maintained between the bar I1 and the arm 22 without depending upon connection through any hinge parts.

In the slot 2!, within a suitable enlargement centrally formed therein, is carried a compression spring 25 against which the switch arm 22 is pressed to permit the free end of the arm to be carried under a shoulder 26 formed on the lower end of the element ll, Fig. 5.

0n the side of the body I opposite that side 4" carrying the terminal prong H is mounted a second terminal prong 21 to extend along the groove in that side of the body and there be secured in position to have its lower end extending a distance below the lower end of the body preferably equal to the extension of the prong M. This prong 21 is secured to the body ill by any suitable means such as by the screw 28 which passes through the prong and screw-threadedly engages in the body in.

An L-shaped conductor 29 has one end secured against the upper end of the prong 21 by means of a screw 30 passing through the conductor 29 and screw-threadedly engaging the prong 21. The other end of the conductor 29 is compressively carried against the upper end of the bar I! and there secured by means of the screw 3| which likewise extends through the conductor and screw-threadedly engages with the bar I'I. Thus it is to be seen that an electrical circuit is established beginning with the terminal prong l4 and continuing through the element H, the switch arm 22 when engaged under the shoulder 26, the flexible conductor l8, the plate II, the conductor 29, and finally the other prong 27. This is the normal circuit for current fiow below the predetermined point at which the switch arm 22 is released from under the shoulder 26 when the element I! is sufiiciently heated as to cause it to bend around away from the arm.

The element H is initially given a position which will cause it to compressively bear against a stop 32, here shown as a rib extending transversely across the groove I2. In other words, the innermost position of the element II is fixed by its bearing against this rib 32. Preferably, although not necessarily so, the element H is slotted throughout its major length along the groove l2 in order to provide quicker cooling and also to provide against tendency of the element to twist about its own axis. It is desired that the element present the line of contact along its shoulder 26 parallel with the end of the arm 22 in order to maintain the proper current conducting capacity of the circuit. The spring 25 will, of course, flip the switch arm 22 downwardly or outwardly around its hinge connection when the element H bends away from the body l0 sufllciently to release the arm.

The entire structure so far described is preferably mounted upon some suitable base 36. In the form as shown in Figs. 1-6, a base 36 is provided through which the terminal prongs H and 27 may pass freely to bring the head 20 down against the upper or inner side of the base 36 and then have suitable detents 33 and 34 on the respective prongs engage against the outer face of the base 36 to hold the base snugly against the head 20. An enclosing housing 35, preferably made out of some suitable insulating material, is slipped over the switch assembly and down around the periphery of the base 36, here shown as screw-threadedly engaging the base. This base 36 carries centrally a button 31 in a sliding manner to have an inner head in the path of the arm 22 as a means for pushing the arm 22 back into engagement under the shoulder 26 after these members have been released as above explained. It is necessary that either the base 36 or the housing 35, or both as the case may be,

extend suificiently beyond the end of the button 31 when in its innermost position as will permit that button 31 to be carried outwardly upon release of the arm 22 so that such outward travel of the button 31 is not interfered with by any outside member such as the receptacle (not shown) which would receive the prongs l4 and 21.

This form of the invention may then be plugged into a receptacle 38, Fig. 1, which is mounted on a conduit fitting 39 at the device to be protected such as the motor 48. For example, should the motor 40 be stalled and thereby cause the circuit to be interrupted by reason of the element ll becoming heated and releasing the arm 22, the entire device, generally desig' nated by the numeral 4| may be withdrawn from the receptacle 38, the button 31 pushed inwardly to reset the switch, and then the device 4| may be returned to the receptacle 38 to re-establish the circuit. The receptacle 38 would be connected into the circuit, as indicated in Fig. 7, in one side thereof whereby release of the switch arm 22 will interrupt the side of the circuit in which it is placed.

While I have herein shown and described my invention in detail as relating to the one particular form, it is entirely obvious that structural changes may be employed without departing from the spirit of the invention and I, therefore, do not desire to be limited to that precise form beyond the limitations as may be imposed by the following claims.

I claim:

1. In a portable reset circuit breaker, a thermostatic responsive bar bendable upon being heated by a predetermined overload electrical current, a body on which said bar is mounted, a switch arm rockably carried by the body, a shoulder on said bar under which an end of said arm may engage, a spring carried by said body normally urging said arm against said shoulder, a connector in electrical circuit with said arm, a terminal connecting prong carried by said body and electrically connected with said bar, a second terminal prong carried by said body, means electrically connected with said second prorg and said connector, a housing surrounding said body and its parts assembled thereon to have said prongs extend in parallel relation a distance be yond the housing, and a reset button positioned between said prongs in the path of said arm whereby said arm may be pushed by the button into said shoulder engagement in opposition to said spring.

2. In a portable reset circuit breaker, a thermostatic responsive bar bendable upon being heated by a predetermined overload electrical current, a body on which said bar is mounted, a switch arm rockably carried by the body, a shoulder on said bar under which an end of said arm may engage, a spring carried by said body normally urging said arm against said shoulder, a connector in electrical circuit with said arm, a terminal connecting prong carried by said body and electrically connected with said bar, a second terminal prong carried by said body, means electrically connected with said second prong and said connector, a housing surrounding said body and its parts assembled thereon to have said prongs extend in parallel relation 9. distance beyond the housing, and a reset button positioned between said prongs in the path of said arm whereby said arm may be pushed by the button into said shoulder engagement in opposition to said spring, said bar being turned over an end of the body and said first prong being also turned over the body to be in contact with the bar at said end, and said connector comprising a plate secured to the body and a flexible conductor between it and said arm, and said electrical connection means between said second prong and said connector comprising a bar extending around the body therebetween.

DURWARD S. RIVERS. 

